N-path switched-RC circuits can realize filters with very high linearity and compression point while they are tunable by a clock frequency. In this paper, both differential and single-ended N-path ...notch filters are modeled and analyzed. Closed-form equations provide design equations for the main filtering characteristics and nonidealities such as: harmonic mixing, switch resistance, mismatch and phase imbalance, clock rise and fall times, noise, and insertion loss. Both an eight-path single-ended and differential notch filter are implemented in 65-nm CMOS technology. The notch center frequency, which is determined by the switching frequency, is tunable from 0.1 to 1.2 GHz. In a 50-Ω environment, the N-path filters provide power matching in the passband with an insertion loss of 1.4-2.8 dB. The rejection at the notch frequency is 21-24 dB, P 1 dB > +2 dBm, and IIP3 > +17 dBm.
A microwave planar bandpass filter (BPF) with in-band-quasi-flat-group-delay characteristics and two-port-quasi-reflectionless behavior for an infinite spectral range is presented. It is composed of ...the in-series cascade connection of three multipath-delay-line transversal filtering sections (TFSs) with Wilkinson-type power-division/combination stages. In this manner, by means of the composite action of these TFSs, an in-band-quasi-Bessel-type bandpass filtering response with multi-transmission-zero (TZ) stopbands and two-port-quasi-absorptive nature for a finite frequency interval is attained. To further extend such quasi-reflectionless bandwidth from dc to infinite theoretically, as well as the stopband range, one-port-quasi-absorptive wide-band filtering cells are inserted at both the input and output accesses of the overall quasi-flat-group-delay BPF. For experimental demonstration purposes, a microstrip prototype centered at 5 GHz is designed, manufactured, and characterized.
We demonstrate a fully tunable microwave photonic bandpass filter fabricated with Si 3 N 4 /SiO 2 waveguides on a chip. The filter is based on coupled resonator optical waveguide architecture ...comprising a chain of eight coupled ring resonators, each with an optical roundtrip length of 21 cm (free spectral range of 1.4 GHz), with an adjustable resonance frequency, and with adjustable power coupling. The passband shows a 3-dB bandwidth of 72 MHz with at least 51-dB out-of-band rejection and features simultaneously a flat-top, a shape factor of 1.9, and a group delay variation smaller than 2 ns.
This article investigates the photovoltaic fed universal active power filter (PV-UAPF) system for enhancing power quality indices. A novel comb filter together with second-order generalized ...integrator (CFSOGI) based instantaneous power balance theory with power angle (IPBTPA) control scheme is implemented. Under distorted or adverse grid conditions, the CFSOGI effectively extracts the phase angle, frequency, and fundamental positive and negative sequence components (FPNSC) to overcome the limitations of adaptive notch filters. Here, a comb filter constitutes a cluster/group of zeros at multiple harmonic frequencies to achieve notch peaks thereby providing superior harmonic rejection ability. Whereas, IPBTPA generates the reference signals to operate the system at dual compensation strategy with or without solar PV. The power angle is used to extract the desired load voltages under grid voltage fluctuations thereby reducing the burden on the shunt converter. Moreover, the hysteresis controller generates the switching pulses based on the calculation of reference and load powers which improves the dynamic performance by maintaining system power balance and effective DC voltage regulation. Besides, reactive power compensation, suppression of harmonic currents and mitigation of grid voltage fluctuations is also carried out to strengthen the system further. The system is also tested in grid voltage interruption for islanding mode to realize a microgrid system. The overall system performance is also validated using simulation and in a real-time experimental set-up, and results are demonstrated under various conditions.
Functional Bayesian Filter Li, Kan; Principe, Jose C.
IEEE transactions on signal processing,
2022, Letnik:
70
Journal Article
Recenzirano
Odprti dostop
We present a general nonlinear Bayesian filter for high-dimensional state estimation using the theory of reproducing kernel Hilbert space (RKHS). By applying the kernel method and the representer ...theorem to perform linear quadratic estimation in a functional space, we derive a Bayesian recursive state estimator for a general nonlinear dynamical system in the original input space. Unlike existing nonlinear extensions of the Kalman filter where the system dynamics are assumed known, the state-space representation for the Functional Bayesian Filter (FBF) is completely learned online from measurement data in the form of an infinite impulse response (IIR) filter or recurrent network in the RKHS, with universal approximation property. Using a positive definite kernel function satisfying Mercer's conditions to compute and evolve information quantities, the FBF exploits both the statistical and time-domain information about the signal, extracts higher-order moments, and preserves the properties of covariances without the ill effects due to conventional arithmetic operations. We apply this novel kernel adaptive filtering (KAF) to recurrent network training, chaotic time-series estimation and cooperative filtering using Gaussian and non-Gaussian noises, and inverse kinematics modeling. Simulation results show FBF outperforms existing Kalman-based algorithms.
Graph filters are fundamental for extracting and processing signals defined over irregular domains. Most graph filters in the literature are linear, and are usually based on polynomials of the graph ...shift matrix. Autoregressive Moving Average (ARMA) graph filters are a generalization of polynomial filters, but are still linear. In this work, we propose a nonlinear graph filter that is an extension of the order one ARMA graph filter, to give the Median Autoregressive Graph Filter (MAF). The proposed MAF has a similar localization property to the linear counterpart, and can be implemented in a distributive manner. Though strictly nonlinear, the MAF has some linear-like properties, which will be formally proven in this work. Application of the proposed MAF to the denoising of real-world sensor network datasets will be presented. Comparisons with the linear counterpart will also be made.
This paper applies finite control set model predictive control (FCS-MPC) for dynamic reactive power compensation using a hybrid active power filter (HAPF). The FCS-MPC uses a model based on ...LCL-filter equations to predict the system behavior and optimize the control action. In fact, the application of FCS-MPC in grid-connected converters with LCL-Filter is quite recent. This algorithm is a very promising control technique for power electronics converters and its use for reactive power control of hybrid filter has not been reported in the literature yet. This paper uses the FCS-MPC in a multivariable structure along with an adaptive notch filter to damp resonance. The main purpose is to improve the dynamic response of the HAPF. Simulation as well as practical results prove the feasibility of FCS-MPC application in HAPF reactive power control. The dynamic response of the equipment was significantly improved and represents the main contribution of this paper. As a result, the FCS-MPC allows tracking fluctuations and abrupt changes in load reactive power.
A class of RF broad-band bandpass filter (BPF) with quasi-elliptic-type response in low-cost bulk CMOS technology is reported. It is based on the in-series cascade connection of lowpass and highpass ...filtering stages with 3-D inductors, whose parasitic capacitances are properly exploited. Specifically, they are used to transform the basic inductor into an LC tank, thus allowing to generate an upper transmission zero (TZ) that increases filtering selectivity and out-of-band power-rejection levels in a spurious-free/extended upper stopband. The layout of a basic third-order BPF cell shaped by four 3-D inductors and its lossless equivalent lumped-element circuit are detailed. By means of this lossless equivalent lumped-element model, its scalability to higher-order BPF designs by in-series cascading various BPF-cell replicas is also demonstrated. For experimental-validation purposes, an on-chip RF CMOS BPF prototype with 11-GHz center frequency and 68.5% 3-dB fractional bandwidth is developed using a 0.13-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> bulk CMOS technology. According to the measured results, it shows an upper stopband with minimum attenuation of 31.7 dB from 22.5 GHz to 67 GHz, alongside with TZs at 3.5 GHz and 22.5 GHz to produce sharp-rejection filtering.
Surface acoustic wave (SAW)-based bandpass filters (BPFs) with symmetrical quasi-reflectionless characteristics and continuously tunable bandwidth (BW) are reported. They are based on ...in-series-cascaded symmetrical quasi-reflectionless acoustic-wave (AW)-lumped-element resonator (AWLR)-based networks whose input and output ports are connected to resistively terminated AWLR-based bandstop filter (BSF) sections. The proposed concept is presented through the coupling routing diagram (CRD) formalism that allows their design using coupled-resonator-based synthesis. It is shown that by incorporating variable reactance elements in their BPF sections, continuous-type BW tuning can be realized. In addition, the fractional BW (FBW) of the filter can be designed to be wider than the electromechanical coupling coefficient <inline-formula> <tex-math notation="LaTeX">k_{t}^{2} </tex-math></inline-formula> of its SAW resonators. This allows enhanced-FBW passbands to be obtained. For proof-of-concept validation, two prototypes were designed and measured. They include a single-stage prototype with 1.9:1 continuously tunable BW and a static two-stage with effective quality factor > 6500, FBW of <inline-formula> <tex-math notation="LaTeX">1.2k_{t}^{2} </tex-math></inline-formula>, and return loss >15 dB throughout its passband and stopband ranges.
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